Currently, in satellite digital video delivery systems, a user or subscriber installs a small parabolic reflector and special electronics at the premises. These systems use the direct broadcast satellite “DBS” spectrum to deliver digital video signals to a user. In these systems, all of the available programming content is transmitted directly to all users from specialized satellites in, for example, a geosynchronous earth orbit. Geosynchronous orbit refers to an orbit in which a satellite orbiting the earth remains in a fixed position relative to a point on the earth. A receiver unit located at the user premises decodes the data stream in order to extract the desired programming.
It is important in digital broadcasting to control the rate at which digital data packets are transmitted. In the absence of real content in a broadcast stream, it is generally practiced to insert a null packet in order to maintain a periodic data rate. It is generally known to calculate an insertion timing and then insert a null packet into the coded data thereby maintaining a desired data rate.
However, a significant disadvantage to this method is that the null packet, which contains useless data, takes up valuable bandwidth. In DBS, the availability of bandwidth is limited and with increased users and content, it is important to efficiently utilize all the bandwidth that is available. The insertion of null packets diminishes the effective bandwidth of the broadcast stream.
Another disadvantage to the null packet insertion method, is that the null packet insertion rate and their duration are non-deterministic. This means that a receiver receiving the data may not have the buffer capacity to handle the amount of data queued. The result is a highly undesirable interruption in service to a subscriber.
There is a need for a method of maximizing the broadcast stream bandwidth without incurring buffer overflow.